Grace

At the appointment of Aaron and his sons shall be all the service of the sons of the Gershonites, in all their burdens, and in all their service:  and ye shall appoint unto them in charge all their burdens.  Numbers 4:27.

The Gershonites were experts at grace.
What is the connection between appointment, service and burdens?
The Gershonites received their assignments from Aaron the high priest of the tabernacle.  The Gershonites under authority were assigned burdens.  All the burdens that were assigned to them were appointed by Aaron.  When they carried the burdens that were assigned to them they were operating under authority and they had the power to carry it out.
The power of God is available to lift burdens.  As long as we operate under the principle of authority and our lifting the burdens assigned to us.  
Jesus, our Great High Priest, knows our strengths and our weaknesses.  When He assigns us a task He also gives the power to accomplish it.  That power is His grace.  Grace is God's empowerment to accomplish what would be humanly impossible.